I just purchased a new to me MC and trailer and hooked it up for the first time. It's dark and I can't see for sure, but it looks like the 7 pin connector on the trailer only has 5 electrical connections. It has the slots for all 7, but there is no metal piece inside with which to make a circuit. I have running lights on the side and rear, but no left or right turn blinkers, no brake lights, and no reverse light.

Anyone else have this? Is there a reason somebody would have done this intentionally? I can see one or more of the electrodes breaking under use, but it doesn't look heavily used. On the other hand, nothing comes to mind why somebody would do this to their trailer on purpose. I don't find it possible the trailer was built this way so I likely just have to replace the 7 pin connector... I'm assuming the wires are in there somewhere and active, just not currently connected.

Now that I think about it, the previous owner did mention something about electronic brakes, but then reversed course and said he was thinking of his other trailer... Wondering if he disabled the brake lights for some reason because he had a different set up for brakes. Im not familiar with what electronic brakes even implies.

5 connections in a 7 way adapter is normal can't tell you what's wrong with your trailer lights as anyone will tell you trailer lights are evil

As for trailer brakes they aren't electronically engaged because they are what's called surge brakes they work with the weight of the boat pushing open and closed the cylinder in the tongue but the brakes are electrically dis-engaged when in reverse

5 connections in a 7 way adapter is normal can't tell you what's wrong with your trailer lights as anyone will tell you trailer lights are evil

As for trailer brakes they aren't electronically engaged because they are what's called surge brakes they work with the weight of the boat pushing open and closed the cylinder in the tongue but the brakes are electrically dis-engaged when in reverse

Hope this helps

I know the trailer brakes are SUPPOSED to be surge brakes, but I'm trying to figure out what the prior owner modified on this trailer. I'm fairly certain the prior owner modified the 7 pin connector to remove a couple important connections, but I can't figure out why. I need to figure out whether he also modified anything else. I don't want to go barreling down the highway and discover the hard way that he replaced the surge brakes with electric brakes since I have no brake controller.

I've got a question out to the PO as well, but he's not responding yet.

It might be that the person used a 7 pin connector for wires that were intended to be in a 4 pin connector. My boat trailer was hooked up like this when i bought it (used). It actually had 5 wires hooked up but only 4 were needed.

Your plug is a wired converted adapter. I have a 7 pin female connector with a 4 pin plug. I don't need 5 or even 7. When I add reverse lights and some other bling to the trailer I will be changing to a 5 or even full 7 connection plug.

__________________...A bad day water skiing still beats a good day at work...1995 Pro Star 205....

These trailers only need 4 wires hooked up, 5 if it has disk brakes or reverse lights. Ground, running lights, left turn/stop, right turn/stop, and reverse is the fifth if it has disk brakes or back-up lights. My guess is either there are some bad connections (pretty good possibility if its the first time being used this year), or the wires are just in a different spot on the plug. I would grab a multimeter or test light and start testing.

I had this on my wife's car. For whatever reason, the car plug connector had the wires in the incorrect order. I pulled the car plug and boat plug apart and matched the car plug to the boat plug. You could also easily do this with a wiring diagram, too.